产酱香地衣芽孢杆菌CGMCC 3963耐受特征及基于转录组学的耐受机制分析

Tolerance characteristics of Bacillus licheniformis CGMCC 3963 and tolerance mechanisms based on transcriptome analysis

摘要:

【目的】地衣芽孢杆菌是茅台酒高温大曲中能产酱香风味物质的主要微生物，对酱香型白酒的酿造具有重要价值。而酱香型白酒的酿造环境具有高渗、高温、酸性、高乙醇胁迫等特征，研究产酱香地衣芽孢杆菌在环境胁迫下的耐受特征有利于认识酱香型白酒的酿造特征。【方法】以一株产酱香地衣芽孢杆菌(Bacillus licheniformis CGMCC 3963)为研究对象，测定其耐渗、耐酸、耐乙醇特征，并从比较转录组学角度系统分析B. licheniformis CGMCC 3963的耐受机制。【结果】B. licheniformis CGMCC 3963在15%的KCl、15%的NaCl、pH 4.0的酸性环境或6%乙醇浓度下的生长情况明显优于不产酱香的模式菌株B. licheniformis ATCC 14580。转录组比较分析显示B. licheniformis CGMCC 3963中一系列与耐受相关的基因表达有差异。【结论】来源于酿造环境的B. licheniformis CGMCC 3963耐受能力强于B. licheniformis ATCC 14580，一系列与耐受相关的基因表达有差异。编码脯氨酸和甜菜碱等溶质转运、离子外排、钾离子通道蛋白等基因的差异表达，使得高渗胁迫下B. licheniformis CGMCC 3963生长明显优于B. licheniformis ATCC 14580；编码II类热休克蛋白、乙醇脱氢酶、氧化应激、pH动态平衡等相关基因的差异表达，在提高菌株耐受酸性环境能力上起了重要作用；II类及III类热休克基因的高表达对B. licheniformis CGMCC 3963耐乙醇能力起了重要作用。

Abstract:

[Objective] Bacillus licheniformis is the predominant microbe producing Maotai-flavor in high-temperature Daqu which plays important roles in Maotai-flavor liquor making. Learing the machanisms of tolerance to this liquor making environment with hypertonic, acid and ethanol stress would provide an insight into characterisitcs of this liquor making. [Methods] The resistance to hypertonic, acid and ethanol of B. licheniformis CGMCC 3963 which produces Maotai-flavor was measured. the tolerance machanisms were analyzed on comparative transcriptomics level. [Results] The growth of B. licheniformis CGMCC 3963 in 15% KCl, 15% NaCl, pH 4.0 or 6% ethanol concentration was significantly better than that of B. licheniformis ATCC 14580. Comparative transcriptome analysis revealed a series of genes differently expressed in B. licheniformis CGMCC 3963. [Conclusion] Compared with B. licheniformis ATCC 14580, B. licheniformis CGMCC 3963 posessed a stronger tolerance ability and differently expressed a series of genes related to stress tolerance. Differently expressed genes encoding solute transport, potassium channel protein played important roles in imoproving the tolerance to osmotic stress; genes related to class II heat shock proteins, dehydrogenase, oxidative stress and pH homeostasis made significant contributions to the resistance to acid of B. licheniformis CGMCC 3963; class II and class III heat shock genes were important to ethanol tolerance ability of B. licheniformis CGMCC 3963.